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ABSTRACT The article analyses the possibility of using geopolymers as a matrix of sprayed concretes intended for realisation of constructions in the environment with an increased fire risk. Thanks to their specific properties, geopolymers... more
ABSTRACT The article analyses the possibility of using geopolymers as a matrix of sprayed concretes intended for realisation of constructions in the environment with an increased fire risk. Thanks to their specific properties, geopolymers show a high resistance to extreme temperatures. Thus, using geopolymers as a matrix shows a considerable potential in the light of development of sprayed concretes resistant to high temperatures.
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The ratio between the relaxed enthalpy and volume (so-called aging modulus, K a) was expressed in frame of the Tool-Narayanaswamy-Moynihan theory. The common case where various experimental arrangements are used for measuring these... more
The ratio between the relaxed enthalpy and volume (so-called aging modulus, K a) was expressed in frame of the Tool-Narayanaswamy-Moynihan theory. The common case where various experimental arrangements are used for measuring these quantities was analyzed. It was found that relatively small differences between the conditions of enthalpy and volume relaxation experiments may cause a significant shift of observed K a value. The sensitivity of K a modulus to the difference between the enthalpy and volume relaxation conditions is significantly higher in the case of organic polymeric glasses in comparison with silicate and chalcogenide glasses. The reason for such grouping resides in higher values of glass transition temperature and lower values of activation enthalpy of inorganic glasses.
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The microstructures of reactive magnesia cement blends, consisting of mixtures of a reactive magnesium oxide (MgO), Portland cement (PC) and pulverised fuel ash (pfa), as observed with scanning electron microscopy are reported. To allow... more
The microstructures of reactive magnesia cement blends, consisting of mixtures of a reactive magnesium oxide (MgO), Portland cement (PC) and pulverised fuel ash (pfa), as observed with scanning electron microscopy are reported. To allow identification of the hydration products of MgO, mixtures of pfa and MgO only were also studied and mixtures of PC and pfa were included as a
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ABSTRACT
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Behavior of iodine fission product is of prime importance for short-term radiological consequences in a severe accident occurring on a pressurized water nuclear reactor. Iodine speciation in the reactor coolant system is commonly... more
Behavior of iodine fission product is of prime importance for short-term radiological consequences in a severe accident occurring on a pressurized water nuclear reactor. Iodine speciation in the reactor coolant system is commonly predicted with severe accident simulation software ...
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... the example of its application on the chalcogenide glasses from the pseudobinary system As2S3 ...Under the glass transition region characterized by the glass transition temperature Tg the glass ... is (supposing the standard state of... more
... the example of its application on the chalcogenide glasses from the pseudobinary system As2S3 ...Under the glass transition region characterized by the glass transition temperature Tg the glass ... is (supposing the standard state of pure substance at standard pressure and temper ...
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The structure of chalcogenide glasses in the pseudo-binary system As2S3-As2Se3 was investigated by comparison of the results of the thermodynamic model of Shakhmatkin & Vedishcheva with the results obtained by the analysis of Raman... more
The structure of chalcogenide glasses in the pseudo-binary system As2S3-As2Se3 was investigated by comparison of the results of the thermodynamic model of Shakhmatkin & Vedishcheva with the results obtained by the analysis of Raman spectra of xAs2S3.(1-x)As2Se3 (x=1, 0·75, 0·5, 0·33, 0·25 and 0) glasses performed by the PCA (principal component analysis) method and spectral decomposition by the method of Zakaznova-Herzog & Malfait. The PCA method identified three independent components in the studied spectral series. On the other hand, the thermodynamic modelling resulted in four components with significant abundance in the studied glasses, i.e. Se, As2S2, As2S3, and As2Se3. Finally, a correlation analysis showed a strong (correlation coefficient of 0·97) linear dependence between the concentrations of Se and As2S2. Using the method of Malfait, partial Raman spectra of (Se+As2S2), As2S3 and As2Se3 were calculated. The experimental spectra were reproduced with excellent accuracy. The...
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The temperature dependence of viscosity of three compositional series of PbO–WO3–P2O5 glasses with compositions (0·5–x/2) PbO.xWO3.(0·5–x/2)P2O5, x=0, 0·1, 0·2, 0·3, 0·4, 0·5, 0·6; 0·5PbO.xWO3.(0·5–x)P2O5, x=0·1, 0·2, 0·3; and... more
The temperature dependence of viscosity of three compositional series of PbO–WO3–P2O5 glasses with compositions (0·5–x/2) PbO.xWO3.(0·5–x/2)P2O5, x=0, 0·1, 0·2, 0·3, 0·4, 0·5, 0·6; 0·5PbO.xWO3.(0·5–x)P2O5, x=0·1, 0·2, 0·3; and (0·5–x)PbO.xWO3.0·5P2O5, x=0·1, 0·2, 0·3, 0·4 measured by thermomechanical analysis is reported. The Andrade viscosity equation was successfully used to describe the temperature dependence of viscosity and to evaluate of the temperature independent activation energy for viscous flow. The results are discussed in terms of the glass structure by considering the network forming/modifying function of individual oxides. A simplified structural model is proposed and verified by a multilinear regression analysis of the compositional dependence of the activation energy for viscous flow and the glass transition temperature.
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The isothermal nucleation of an As2Se3 undercooled melt followed by crystallization and consequent melting was followed by DSC using a constant heating rate. The melting enthalpy was used to quantify the degree of conversion, α. Nonlinear... more
The isothermal nucleation of an As2Se3 undercooled melt followed by crystallization and consequent melting was followed by DSC using a constant heating rate. The melting enthalpy was used to quantify the degree of conversion, α. Nonlinear regression analysis of the dependence of conversion on isothermal nucleation temperature and time was performed on the basis of classical nucleation theory assuming normal 3D growth. The parameters for the temperature dependence of nucleation rate and growth rate were determined by a three step process. First the simple parabolic model was used to estimate the maximum and the width of rate-temperature curve. Then the obtained parabolic curves were fitted by theoretical ones. In the third step the parameters obtained in the previous steps were used for nonlinear regression analysis of the experimental data. The kinetic barrier of crystal growth was found to be in agreement with the activation energy for viscous flow.
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... since 2008/Apr/08 at www.scientific.net © (2008) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.39-40.173 ... Refractive index was measured on polished prismatic glass samples by Abbe's refractometer at... more
... since 2008/Apr/08 at www.scientific.net © (2008) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.39-40.173 ... Refractive index was measured on polished prismatic glass samples by Abbe's refractometer at 20°C. Chemical durability against water, CD ...
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We present a new methodology of determination of hot-cracking of metallic materials, which is based on laboratory application of the wedge rolling test and computer processing of the results obtained. The experiment was made with selected... more
We present a new methodology of determination of hot-cracking of metallic materials, which is based on laboratory application of the wedge rolling test and computer processing of the results obtained. The experiment was made with selected new types of high-alloyed free-cutting (ferritic and austenitic) steels. The initial specimens underwent an additional modification enabling easier development of cracks which consisted in
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Determination of Fracture Toughness and Fracture Probability of LPS Aluminas by Hertzian Indentation ... precisely, but that it is also difficult, and in real experiment virtually impossible, to identify unambiguously the correct crack... more
Determination of Fracture Toughness and Fracture Probability of LPS Aluminas by Hertzian Indentation ... precisely, but that it is also difficult, and in real experiment virtually impossible, to identify unambiguously the correct crack geometry (Palmquist, or half-penny), and hence, to ...
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The enthalpic relaxation of the title glasses, studied by differential scanning calorimetry, is well described by a mathematical model based on the stretched exponential relaxation function with the relaxation time proportional to the... more
The enthalpic relaxation of the title glasses, studied by differential scanning calorimetry, is well described by a mathematical model based on the stretched exponential relaxation function with the relaxation time proportional to the actual viscosity. The dependence of viscosity on temperature and the fictive temperature was expressed by Mazurin's approximation. The relaxation parameters obtained correlated significantly with the glass composition, indicating the changes in the structural of the TiO2 role near a TiO2 content of 3–4 mol%.